Hybrid Cathodes Composed of K3V2(PO4)3 and Carbon Materials with Boosted Charge Transfer for K-Ion Batteries

Xianghua Zhang,Qi Zhang,Ni Xiao,Yan Yu,Hanwen Zhu,Xinyi Kuang,Shaoming Huang,Xianhong Rui

doi:10.3390/surfaces3010001

Abstract

K-ion batteries (KIBs) have emerged as an auspicious alternative to Li-ion batteries (LIBs) owing to their uniform distribution, plentiful reserves, the low cost of K resources, and their similar physicochemical properties to Li resources. The development of KIBs is seriously limited by cathode materials. Here, a hybrid of K3V2(PO4)3 (KVP) particles triple-coated by amorphous carbon, carbon nanotubes (CNTs), and reduced graphene oxide (rGO) nanosheets (KVP/C/CNT/rGO) was fabricated by a facile ball milling process followed by heat treatment. Consequently, a stable capacity of 57 mAh g−1 can be achieved at 0.2C, and a slow capacity decaying rate (0.06% per cycle) is displayed during 500 cycles under a high current density of 5C. The remarkable reversible capacity and excellent long-term cycling life are mainly due to the enhanced interwoven C/CNT/rGO networks and superior KVP crystal structure stability, which can provide multi-channel for fast electron transport and effective K+ diffusion.

Highlights

The requirement for energy storage devices (e.g., Li-ion batteries (LIBs)) is increasing rapidly with the fast development of electric vehicles [1,2,3]
Thermogravimetry (TG) analysis was tested in an air atmosphere to ascertain the total amount of C/carbon nanotubes (CNTs)/reduced graphene oxide (rGO) in the composite
There is only about 0.06% capacity decaying per cycle within 500 charge–discharge processes

Summary

Introduction

The requirement for energy storage devices (e.g., Li-ion batteries (LIBs)) is increasing rapidly with the fast development of electric vehicles [1,2,3]. New concerns have been activated that the widespread use of LIBs may not satisfy the large-scale demand tomorrow because of uneven distribution, limited reserves, and the increasing cost of lithium minerals [4,5,6,7,8,9]. Many efforts have been made to exploring standout alternatives to LIBs. Rechargeable K-ion batteries (KIBs) have provoked tremendous interest due to the similar physical and chemical characters to Li and the abundant reserves of K resources [10,11,12]. Standard electrode potential of potassium (−2.94 V vs. E◦ ) is close to that of lithium (−3.04 V vs. E◦ ), indicating comparable working voltage for KIBs [13,14,15].

Methods

Results

Conclusion